#private

In a company of three, two should not speak privately leaving out the third in their presence

bukhari:6288ʿAbdullāh b. Yūsuf > Mālik > Ismāʿīl > Mālik > Nāfiʿ > ʿAbdullāh

the Prophet ﷺ said, "When there are three persons, then two of them should not speak privately excluding the third."  

البخاري:٦٢٨٨حَدَّثَنَا عَبْدُ اللَّهِ بْنُ يُوسُفَ أَخْبَرَنَا مَالِكٌ وَحَدَّثَنَا إِسْمَاعِيلُ قَالَ حَدَّثَنِي مَالِكٌ عَنْ نَافِعٍ عَنْ عَبْدِ اللَّهِ ؓ

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ: «إِذَا كَانُوا ثَلاَثَةٌ فَلاَ يَتَنَاجَى اثْنَانِ دُونَ الثَّالِثِ۔»